Characterisation and seasonal variations of particles in the atmosphere of rural, urban and industrial areas: Organic compounds

Long- and Intermediate-Term Ambient Particulate Pollution Is Associated with Increased Osteoarthritis Risk: A Population-Based Prospective Analysis

Recent studies found the intrusion and retention of exogenous fine particles into joints, but epidemiological data for long- and intermediate-term exposure associations are scare. Here, all urban working, retired employee, and rural residents (16.78 million) in Beijing from January 1, 2011 to December 31, 2019 were included to investigate the effects of long- and intermediate-term ambient particulate exposure on development of osteoarthritis. We identified 1,742,067 participants as first-visit patients with osteoarthritis. For each interquartile range increase in annual PM2.5 (23.32 μg/m3) and PM10 (23.92 μg/m3) exposure concentration, the pooled hazard ratios were respectively 1.238 (95% CI: 1.228, 1.249) and 1.178 (95% CI: 1.168, 1.189) for first osteoarthritis outpatient visits. Moreover, age at first osteoarthritis outpatient visits significantly decreased by 4.52 (95% CI: 3.45 to 5.40) days per μg/m3 for annual PM2.5 exposure at below 67.85 μg/m3. Finally, among the six constituents analyzed, black carbon appears to be the most important component associated with the association between PM2.5 exposure and the three osteoarthritis-related outcomes.

Association between ambient PM1 and the prevalence of chronic kidney disease in China: A nationwide study

Particulate of diameter ≤ 1 µm (PM1) presents a novel risk factor of adverse health effects. Nevertheless, the association of PM1 with the risk of chronic kidney disease (CKD) in the general population is not well understood, particularly in regions with high PM1 levels like China. Based on a nationwide representative survey involving 47,204 adults and multi-source ambient air pollution inversion data, the present study evaluated the association of PM1 with CKD prevalence in China. The two-year average PM1, particulate of diameter ≤ 2.5 µm (PM2.5), and PM1-2.5 values were accessed using a satellite-based random forest approach. CKD was defined as estimated glomerular filtration rate < 60 ml/min/1.73 m2 or albuminuria. The results suggested that a 10 μg/m3 rise in PM1 was related to a higher CKD risk (odds ratio [OR], 1.13; 95% confidence interval [CI] 1.08-1.18) and albuminuria (OR, 1.11; 95% CI, 1.05-1.17). The association between PM1 and CKD was more evident among urban populations, older adults, and those without comorbidities such as diabetes or hypertension. Every 1% increase in the PM1/PM2.5 ratio was related to the prevalence of CKD (OR, 1.03; 95% CI, 1.03-1.04), but no significant relationship was found for PM1-2.5. In conclusion, the present study demonstrated long-term exposure to PM1 was associated with an increased risk of CKD in the general population and PM1 might play a leading role in the observed relationship of PM2.5 with the risk of CKD. These findings provide crucial evidence for developing air pollution control strategies to reduce the burden of CKD.

Road-traffic-related air pollution contributes to skin barrier alteration and growth defect of sensory neurons

The effects of air pollution on health are gaining increasing research interest with limited data on skin alterations available. It was suggested that air pollution is a trigger factor for sensitive skin (SS). However, this data was based on surveys with a lack of experimental data. SS is related to altered skin nerve endings and cutaneous neurogenic inflammation. TTe present study was to assess the in vitro effect of particulate matter (PM) on epidermis and nerve ending homeostasis. PM samples were collected according to a validated protocol. Reconstructed human epidermis (RHE, Episkin®) was exposed to PM and subsequently the supernatants were transferred to a culture of PC12 cells differentiated into sensory neurons (SN). Cell viability, axonal growth and neuropeptide-release were measured. The modulation of the expression of different inflammatory, keratinocytes differentiation and neurites growth markers was assessed. PM samples contained a high proportion of particles with a size below 1 μm and a complex chemical composition. Transcriptomic and immunohistochemical analyses revealed that PM altered keratinocytes terminal differentiation and induced an inflammatory response. While viability and functionality of the SN were not modified, their outgrowth was significantly decreased after incubation with PM-exposed Episkin® supernatants. This was closely related to the modification of nerve growth factor/semaphorin 3A balance. This study showed that air pollutants have negative effects on keratinocytes and sensory nerve endings including inflammatory responses. These effects are probably involved in the SS pathophysiology and might be involved in inflammatory skin disorders.

Oxidative stress and inflammation induced by air pollution-derived PM2.5 persist in the lungs of mice after cessation of their sub-chronic exposure

More than 7 million early deaths/year are attributable to air pollution. Current health concerns are especially focused on air pollution-derived particulate matter (PM). Although oxidative stress-induced airway inflammation is one of the main adverse outcome pathways triggered by air pollution-derived PM, the persistence of both these underlying mechanisms, even after exposure cessation, remained poorly studied. In this study, A/JOlaHsd mice were also exposed acutely (24 h) or sub-chronically (4 weeks), with or without a recovery period (12 weeks), to two urban PM2.5 samples collected during contrasting seasons (i.e., autumn/winter, AW or spring/summer, SS). The distinct intrinsic oxidative potentials (OPs) of AW and SS PM2.5, as evaluated in acellular conditions, were closely related to their respective physicochemical characteristics and their respective ability to really generate ROS over-production in the mouse lungs. Despite the early activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) cell signaling pathway by AW and, in a lesser degree, SS PM2.5, in the murine lungs after acute and sub-chronic exposures, the critical redox homeostasis was not restored, even after the exposure cessation. Accordingly, an inflammatory response was reported through the activation of the nuclear factor-kappa B (NF-κB) cell signaling pathway activation, the secretion of cytokines, and the recruitment of inflammatory cells, in the murine lungs after the acute and sub-chronic exposures to AW and, in a lesser extent, to SS PM2.5, which persisted after the recovery period. Taken together, these original results provided, for the first time, new relevant insights that air pollution-derived PM2.5, with relatively high intrinsic OPs, induced oxidative stress and inflammation, which persisted admittedly at a lower level in the lungs after the exposure cessation, thereby contributing to the occurrence of molecular and cellular adverse events leading to the development and/or exacerbation of future chronic inflammatory lung diseases and even cancers.

Exposure to ambient air pollutants is associated with an increased incidence of hyperuricemia: A longitudinal cohort study among Chinese government employees

BACKGROUND

It is widely recognized that ambient air pollution can induce various detrimental health outcomes. However, evidence linking ambient air pollutants and hyperuricemia incidence is scarce.

OBJECTIVES

To assess the association between long-term air pollution exposure and the risk of hyperuricemia.

METHODS

In this study, a total of 5854 government employees without hyperuricemia were recruited and followed up from January 2018 to June 2021 in Hunan Province, China. Hyperuricemia was defined as serum uric acid (SUA) level of >420 μmol/L for men and >360 μmol/L for women or use of SUA-lowering medication or diagnosed as hyperuricemia during follow-up. Data from local air quality monitoring stations were used to calculate individual exposure levels of PM10, PM2.5, SO2 and NO2 by inverse distance weightingn (IDW) method. Cox proportional hazard model was applied to evaluate the causal relationships between air pollutant exposures and the risk of hyperuricemia occurrence after adjustment for potential confounders and meanwhile, restricted cubic spline was used to explore the dose-response relationships.

RESULTS

The results indicated that exposures to PM10 (hazard ratio, HR = 1.042, 95% conficence interal, 95% CI: 1.028, 1.057), PM2.5 (HR = 1.204, 95% CI: 1.141, 1.271) and NO2 (HR = 1.178, 95% CI: 1.125,1.233) were associated with an increased HR of hyperuricemia. In addition, a nonlinear dose-response relationship was found between PM10 exposure level and the HR of hyperuricemia (p for nonlinearity = 0.158) with a potential threshold of 50.11 μg/m3. Subgroup analysis demonstrated that participants usually waking up at night and using natural ventilation were more vulnerable to the exposures of PM10, PM2.5, NO2, and SO2.

CONCLUSION

Long-term exposures to ambient PM10, PM2.5 and NO2 are associated with an increased incidence of hyperuricemia among Chinese government employees.

Innovative graph analysis method to assess gene expression modulation after fine particles exposures of 3D human airway epithelia

Environmental particles have dramatic consequences for health, especially for the most vulnerable people, such as asthmatics. To better understand the impact on gene expression modulation of fine particles (PM2.5-0.3) from different emission sources, a 3D-airway model, a human bronchial epithelium (MucilAir-HF™) reconstructed from primary cells from healthy (EpiH) or asthmatic (EpiA) donors, was used. Repeated air-liquid exposures were performed, and epithelia were sacrificed to extract RNAs and assess gene expression. Data were analyzed according to the emission sources, physiological status, and exposure doses using a recent model consisting in a graph analysis on pairwise expression ratio. The results were compared with those from the classical ΔΔCt method. The graph analysis method proved to have better statistical properties than the classical ΔΔCt method and demonstrated that repeated PM2.5-0.3 exposures induced a dose-dependent up-regulation of the metabolic gene (CYP1B1) and a down-regulation of the inflammation gene (CXCL10). These modulations were greater for "industrial" than for "urban traffic" fine particles, and the effects were found to be greater after exposure of EpiA than EpiH, thus emphasizing the importance of the epithelium's physiological status in sensitivity to particles. Our study is original in terms of the experimental conditions and the graphical statistical analysis model established. The results highlight the importance of particle chemistry on the modulation of cellular and molecular responses, which may vary according to the individual's vulnerability.

Associations between short-term exposure of ambient particulate matter and hemodialysis patients death: A nationwide, longitudinal case-control study in China

BACKGROUND

Long-term exposure to particulate air pollutants can lead to an increase in mortality of hemodialysis patients, but evidence of mortality risk with short-term exposure to ambient particulate matter is lacking. This study aimed to estimate the association of short-term exposure to ambient particulate matter across a wide range of concentrations with hemodialysis patients mortality.

METHODS

We performed a time-stratified case-crossover study to estimate the association between short-term exposures to PM_2.5 and PM₁₀ and mortality of hemodialysis patients. The study included 18,114 hemodialysis death case from 279 hospitals in 41 cities since 2013. Daily particulate matter exposures were calculated by the inverse distance-weighted model based on each case's dialysis center address. Conditional logistic regression were implemented to quantify exposure-response associations. The sensitivity analysis mainly explored the lag effect of particulate matter.

RESULTS

During the study period, there were 18,114 case days and 61,726 control days. Of all case and control days, average PM_2.5 and PM₁₀ levels were 43.98 μg/m³ and 70.86 μg/m³, respectively. Each short-term increase of 10 μg/m³ in PM_2.5 and PM₁₀ were statistically significantly associated with a relative increase of 1.07 % (95 % confidence interval [CI]: 0.99 % - 1.15 %) and 0.89 % (95 % CI: 0.84 % - 0.94 %) in daily mortality rate of hemodialysis patients, respectively. There was no evidence of a threshold in the exposure-response relationship. The mean of daily exposure on the same day of death and one-day prior (Lag 01 Day) was the most plausible exposure time window.

CONCLUSIONS

This study confirms that short-term exposure to particulate matter leads to increased mortality in hemodialysis patients. Policy makers and public health practices have a clear and urgent opportunity to pass air quality control policies that care for hemodialysis populations and incorporate air quality into the daily medical management of hemodialysis patients.

Occurrence of organic contaminants bonded to the particulate matter from outdoor air influenced by industrial activities

This paper discusses the occurrence of organic contaminants bonded to particulate matter (PM) in ambient air. We describe the presence and concentration levels of contaminants mainly reported in atmospheres close to factories or at locations influenced by them, and the relationship between factory emissions and the type of organic contaminants found in PM samples from the surrounding air. Many organic contaminants have been found in these types of samples, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs). Their sources, fates and distributions in the ambient atmosphere are therefore well known. However, in addition to these most studied compounds, others are also of concern nowadays due to their detection and toxic effects on the environment. The continuous updating of regulations on these contaminants and the appearance of new air pollutants make it important to be aware of their occurrence. This will help to either establish new guidelines for the newer contaminants or reassess existing limitations for known ones. Moreover, if we know their occurrence, we can analyse their sources, destinations and distributions in the outdoor air.

Variations in traffic-related polycyclic aromatic hydrocarbons in PM2.5 in Kanazawa, Japan, after the implementation of a new vehicle emission regulation

A three-year sampling campaign was conducted at a roadside air pollution monitoring station in the urban area of Kanazawa, Japan. Due to a new emission regulation, PAHs levels decreased over the sampling campaign, exhibiting values of 706 ± 413 pg/m³ in 2017, 559 ± 384 pg/m³ in 2018, and 473 ± 234 pg/m³ in 2019. In each year, similar seasonal variations in PAHs levels were observed, with higher levels observed in winter and lower levels in summer. Among the PAHs isomer ratios, we observed that the ratio of benzo[b]fluoranthene (BbF) and benzo[k]fluoranthene (BkF), [BbF]/([BbF] + [BkF]), and the ratio of indeno[1,2,3-cd]pyrene (IDP) and benzo[ghi]perylene (BgPe), [IDP]/([BgPe] + [IDP]), showed stability over the sampling campaign and were less affected by the new emission regulation, seasonal variations, and regional characteristics. When using the combined ratio ranges of 0.66 - 0.80 ([BbF]/([BbF] + [BkF]) and 0.26-0.49 ([IDP]/([BgPe] + [IDP]), traffic emissions were clearly distinguished from other PAHs emission sources. Principal component analysis (PCA) and positive matrix factorization (PMF) were also performed to further analyse the characteristics of traffic-related PAHs. Overall, this study affirmed the effectiveness of the new emission regulation in the reduction of PAHs emissions and provided a combined range for identifying PAHs traffic emission sources.

Investigation of PAHs, nitrated PAHs and oxygenated PAHs in PM10 urban aerosols. A comprehensive data analysis

Polycyclic aromatic compounds (PACs) in particulate matter contribute considerably to the health risk of air pollution. As such, we have optimized a method to determine the levels of polycyclic aromatic hydrocarbons, especially nitrated and oxygenated polycyclic aromatic hydrocarbons, in samples of PM₁₀ particulate matter using microwave-assisted extraction (MAE) and gas chromatography coupled to a triple quadrupole mass spectrometer (GC-MS/MS). The proposed method was applied to the analysis of real samples collected in the urban area of Ciudad Real (Spain) during one year. The median total concentrations of eighteen PAHs (∑PAHs) and seven OPAHs (∑OPAHs) were 0.54 and 0.23 ng m^-3, respectively, with the corresponding value for NPAH (∑NPAHs) being 0.03 ng m^-3 (only detected in 40% of samples). A clear seasonal trend was observed, with higher levels in the cold season and lower in the warm season for ∑PAHs. The same effect was observed for ∑OPAHs, which exhibited a median concentration of 0.72 ng m^-3 in the cold season and 0.10 ng m^-3 in the warm season, and for ∑NPAH, which exhibited a median of 0.04 ng m^-3 in the cold season but were not detected in the warm season. Molecular diagnostic ratios and PCA (principal component analysis) showed a predominantly traffic origin for PACs. The sources of PAHs also depend on meteorological conditions and/or atmospheric reactions, as confirmed by means of statistical analysis. The ∑OPAH/∑PAH and ∑NPAH/∑PAH ratios were higher in the cold season than the warm season, thus suggesting that PAH derivatives originated from primary combustion emission sources together with their parent PAHs. The concentration range found for benzo(a)pyrene was 0.006-0.542 ng m^-3, which is below the threshold value of 1 ng m^-3 established in European legislation as the annual average value. The lifetime lung risk from inhalation of PM₁₀-bound PACs was estimated to be six cancer cases per million people using the World Health Organization method.

Air pollution levels near crossroads with different traffic density and the estimation of health risk

The aim of this study was to determine the influence of traffic density on air pollutant levels as well as to analyse the spatial and temporal distribution of particulate pollutants and their health risk. The following species related to traffic pollution were measured: PM₁₀, elemental and organic carbon and polycyclic aromatic hydrocarbons (PAHs) in PM₁₀ and gas pollutants (SO₂, NO₂ and CO). The measurements were carried out at four crossroad sites in the city. Samples of PM₁₀ were collected over three periods (6 am to 2 pm, 2 pm to 10 pm and 10 pm to 6 am) on working days and weekends. Statistically significant differences were found between sampling sites for all pollutant concentrations, except for NO₂. The highest mass concentrations of PM₁₀, carbon and PAHs were observed in the south of the city with the highest traffic density. Concentrations of gasses (CO and NO₂) showed high values in morning and in the late afternoon and evening (west and east). At all measuring sites, the highest concentration of particle-bound pollutants was mostly recorded during morning and afternoon, except at the south, where elevated PAHs concentrations were recorded during night period, which indicated that residential heating takes up a portion of pollution sources in this area. Although for most of the pollutants the concentrations varied during the day, statistically significant differences between sampling periods were not found. The highest health risk was obtained at the south, where it was scored as significant.

Polychlorinated biphenyls in indoor dust from urban dwellings of Lahore, Pakistan: Congener profile, toxicity equivalency, and human health implications

This study is the pioneer assessment of the PCBs in indoor dust particles (from air conditioners) of an urbanized megacity from South Asian. The ∑₃₅ PCB concentration ranged from 0.27 to 152.9 ng/g (mean: 24.84 ± 22.10 ng/g). The tri- and tetra-PCBs were dominant homologues, contributing 57.36% of the total PCB concentrations. The mean levels of Σ₈ -dioxin-like (DL), Σ₆ -indicator PCBs and WHO₂₀₀₅ -TEQ for DL-PCBs were 2.22 ± 2.55 ng/g, 9.49 ± 8.04 ng/g and 4.77 ± 4.89 pg/g, respectively. The multiple linear regression indicated a significant correlation of dusting frequency (p = 1.06 × 10-04) and age of the house (p = 1.02 × 10-06) with PCB concentrations in indoor environment. The spatial variation of PCB profile revealed relatively higher concentrations from sites near to illegal waste burning spots, electrical locomotive workshops, and grid stations. Human health risk assessment of PCBs for adults and toddlers through all three exposure routes (ie, inhalation, ingestion, and dermal contact) demonstrated that toddlers were vulnerable to high cancer risk (4.32 × 10^-04 ), while adults were susceptible from low to moderate levels of risk (3.16 × 10^-05 ). Therefore, comprehensive investigations for PCBs in the indoor settings, focusing particularly on the sensitive populations with relationship to the electronic devices, transformers, and illegal waste burning sites, are recommended.

Metal enriched quasi-ultrafine particles from stainless steel gas metal arc welding induced genetic and epigenetic alterations in BEAS-2B cells

Recent evidence has supported welding fume (WF)-derived ultrafine particles (UFP) could be the driving force of their adverse health effects. However, UFP have not yet been extensively studied and are currently not included in present air quality standards/guidelines. Here, attention was focused on the underlying genetic and epigenetic mechanisms by which the quasi-UFP (Q-UFP, i.e., ≤ 0.25 μm) of the WF emitted by gas metal arc welding-stainless steel (GMAW-SS) exert their toxicity in human bronchial epithelial BEAS-2B cells. The Q-UFP under study showed a monomodal size distribution in number centered on 104.4 ± 52.3 nm and a zeta potential of -13.8 ± 0.3 mV. They were enriched in Fe > Cr > Mn > Si, and displayed a relatively high intrinsic oxidative potential. Dose-dependent activation of nuclear factor erythroid 2-related factor 2 and nuclear factor-kappa B signaling pathway, glutathione alteration, and DNA, protein and lipid oxidative damage were reported in BEAS-2B cells acutely (1.5 and 9 μg/cm², 24 h) or repeatedly (0.25 and 1.5 μg/cm², 3 × 24 h) exposed to Q-UFP (p < 0.05). Alterations of the Histone H3 acetylation were reported for any exposure (p < 0.05). Differentially regulated miRNA and mRNA indicated the activation of some critical cell signaling pathways related to oxidative stress, inflammation, and cell cycle deregulation towards apoptosis. Taken together, these results highlighted the urgent need to better evaluate the respective toxicity of the different metals and to include the Q-UFP fraction of WF in current air quality standards/guidelines relevant to the occupational settings.

PM2.5 characterization of primary and secondary organic aerosols in two urban-industrial areas in the East Mediterranean

Primary and secondary organic aerosols in PM_2.5 were investigated over a one-year campaign at Zouk Mikael and Fiaa, Lebanon. The n-alkanes concentrations were quite similar at both sites (26-29 ng/m³) and mainly explained by anthropogenic emissions rather than natural ones. The concentrations of total Polycyclic Aromatic Hydrocarbons (PAHs) were nearly three times higher at Zouk Mikael (2.56 ng/m³) compared to Fiaa (0.95 ng/m³), especially for indeno[1,2,3-c,d]pyrene linked to the presence of the power plant. A characteristic indeno[1,2,3-c,d]pyrene/(indeno[1,2,3-c,d]pyrene + benzo[g,h,i]perylene) ratio in the range 0.8-1.0 was determined for heavy fuel oil combustion from the power plant. Fatty acids and hopanes were also investigated and were assigned to cooking activities and vehicular emissions respectively. Phthalates were identified for the first time in Lebanon with high concentrations at Zouk and Fiaa (106.88 and 97.68 ng/m³ respectively). Moreover, the biogenic secondary aerosols revealed higher concentrations in summer. The total terpene concentration varied between 131 ng/m³ at Zouk Mikael in winter to 469 ng/m³ at Fiaa in summer. Additionnally, the concentrations of the dicarboxylic acids especially for adipic and phthalic acids were more influenced by anthropogenic sources.The analysis of molecular markers and diagnostic ratios indicated that the sites were strongly affected by anthropogenic sources such as waste open burning, diesel private generators, cooking activities, road transport, power plant, and industrial emissions. Moreover, results showed different pattern during winter and summer seasons. Whereas, higher concentrations of biogenic markers were clearly encountered during the summer period.

Phase distribution and risk assessment of PAHs in ambient air of Hamadan, Iran

In the present study, both gaseous and particulate (PM with dae <2.5 µm) phases of polycyclic aromatic hydrocarbons (PAHs) were measured in the ambient air of Hamadan city, Iran. For this reason, two low-volume samplers equipped with glass fiber filters were used for sampling of particulate phase (N = 30) and XAD-2 sorbent tubes were applied for sampling gaseous phase of PAHs (N = 30). The sampling was conducted during warm and cold seasons in 2019. The average of cold/warm season ratios for Σ₁₆PAH and PM concentrations were 1.14 and 0.62, respectively. Summed PAHs concentration were determined to be in the range 0.008-59.46 (mean: 11.61) ng/m³ and 0.05-40.83 (mean: 10.22) ng/m³ for the cold and warm seasons, respectively. A negative Pearson correlation coefficient was obtained for wind speed and relative humidity. The average Benzo (a) Pyrene equivalent carcinogenic (BaP_eq) levels in the cold season were lower than the maximum permissible risk level of 1 ng/m³ for BaP. The BaP toxicity equivalency (ΣBaP_TEQ) and BaP mutagenicity equivalency (ΣBaP_MEQ) appeared to be significantly higher in the cold season (averaging 0.35 and 1.65 ng/m³, respectively) than those in warm season. Health risk assessment was performed for children and adults based on BaP_eq, inhalation cancer risk. The diagnostic ratios of individual PAHs concentration showed that the significant sources of PAH emissions may be related to light duty vehicles (LDVs) in Hamadan. Although, some other sources such as pyrogenic source and petrol combustion were also suggested.

Characterization and source apportionment of single particles from metalworking activities

Industrial metalworking facilities emit a variety of air toxics including volatile organic compounds, polycyclic aromatic hydrocarbons (PAHs) and heavy metals. In order to investigate these emissions, a 1-month multi-instrument field campaign was undertaken at an industrial site in Grande-Synthe, Dunkirk (France), in May and June 2012. One of the main objectives of the study was to provide new information on the chemical composition of particulate matter with aerodynamic diameters smaller than 2.5 μm (PM_2.5) in the vicinity of metalworking facilities. An aerosol time-of-flight mass spectrometer (ATOFMS) was deployed to provide size-resolved chemical mixing state measurements of ambient single particles at high temporal resolution. This mixing state information was then used to apportion PM_2.5 to local metalworking facilities influencing the receptor site. Periods when the site was influenced by metalworking sources were characterised by a pronounced increase in particles containing toxic metals (manganese, iron, lead) and polycyclic aromatic hydrocarbons (PAHs) with a variety of chemical mixing states. The association of specific particle classes with a nearby ferromanganese alloy manufacturing plant was confirmed through comparison with previous analysis of raw materials (ores) and chimney filter particle samples collected at the facility. Particles associated with emissions from a nearby steelworks were also identified. The contribution of local metalworking activities to PM_2.5 at the receptor site for the period when the ATOFMS was deployed ranged from 1 to 65% with an average contribution of 17%, while the remaining mass was attributed to other local and regional sources. These findings demonstrate the impact of metalworking facilities on air quality downwind and provide useful single particle signatures for future source apportionment studies in communities impacted by metalworking emissions.

Long-Term Exposure to Ambient PM2.5 and Increased Risk of CKD Prevalence in China

BACKGROUND

Fine particulate matter (PM_2.5) is an important environmental risk factor for cardiopulmonary diseases. However, the association between PM_2.5 and risk of CKD remains under-recognized, especially in regions with high levels of PM_2.5, such as China.

METHODS

To explore the association between long-term exposure to ambient PM_2.5 and CKD prevalence in China, we used data from the China National Survey of CKD, which included a representative sample of 47,204 adults. We estimated annual exposure to PM_2.5 before the survey date at each participant's address, using a validated, satellite-based, spatiotemporal model with a 10 km×10 km resolution. Participants with eGFR <60 ml/min per 1.73 m² or albuminuria were defined as having CKD. We used a logistic regression model to estimate the association and analyzed the influence of potential modifiers.

RESULTS

The 2-year mean PM_2.5 concentration was 57.4 μg/m³, with a range from 31.3 to 87.5 μg/m³. An increase of 10 μg/m³ in PM_2.5 was positively associated with CKD prevalence (odds ratio [OR], 1.28; 95% confidence interval [CI], 1.22 to 1.35) and albuminuria (OR, 1.39; 95% CI, 1.32 to 1.47). Effect modification indicated these associations were significantly stronger in urban areas compared with rural areas, in males compared with females, in participants aged <65 years compared with participants aged ≥65 years, and in participants without comorbid diseases compared with those with comorbidities.

CONCLUSIONS

These findings regarding the relationship between long-term exposure to high ambient PM_2.5 levels and CKD in the general Chinese population provide important evidence for policy makers and public health practices to reduce the CKD risk posed by this pollutant.

Association between ambient air pollution and hyperuricemia in traffic police officers in China: a cohort study

To evaluate the association between ambient air pollution and hyperuricemia, we prospectively followed 1748 traffic police officers without hyperuricemia at baseline (2009-2014) from 11 districts in Guangzhou, China. We calculated six-year average PM₁₀, SO₂ and NO₂ concentrations using data collected from air monitoring stations. The hazard ratios for hyperuricemia per 10 µg/m³ increase in air pollutants were 1.46 (95% CI: 1.28-1.68) for PM₁₀, 1.23 (95% CI: 1.00-1.51) for SO₂, and 1.43 (95% CI: 1.26-1.61) for NO₂. We also identified changes in the ratio of serum uric acid to serum creatinine concentrations (ua/cre) per 10 µg/m³ increase in air pollutants as 11.54% (95% CI: 8.14%-14.93%) higher for PM₁₀, 5.09% (95% CI: 2.76%-7.42%) higher for SO₂, and 5.13% (95% CI: 2.35%-7.92%) higher for NO₂, respectively. Long-term exposure to ambient air pollution was associated with a higher incidence of hyperuricemia and an increase in ua/cre among traffic police officers.

Atmospheric Concentrations and Health Implications of PAHs, PCBs and PCDD/Fs in the Vicinity of a Heavily Industrialized Site in Greece

Background: Thriassion Plain is considered the most industrialized area in Greece and thus a place where emissions of pollutants are expected to be elevated, leading to the degradation of air quality. Methods: Simultaneous determination of polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), and polychlorinated biphenyls (PCBs) was performed in PM10 samples. SPSS statistical package was employed for statistical analysis and source apportionment purposes. Cancer risk was estimated from total persistent organic pollutants’ (POPs) dataset according to the available literature. Results: POPs concentrations in particulate matter were measured in similar levels compared to other studies in Greece and worldwide, with mean concentrations of ΣPAHs, ΣPCDD/Fs, dioxin like PCBs, and indicator PCBs being 7.07 ng m−3, 479 fg m−3, 1634 fg m−3, and 18.1 pg m−3, respectively. Seasonal variations were observed only for PAHS with higher concentrations during cold period. MDRs, D/F ratios, and principal component analysis (PCA) highlighted combustions as the main source of POPs’ emissions. Estimation of particles’ carcinogenic and mutagenic potential indicates the increased toxicity of PM10 during cold periods, and cancer risk assessment concludes that 3 to 4 people out of 100,000 may suffer from cancer due to POPs’ inhalation. Conclusions: Increased cancer risk for citizens leads to the necessity of chronic POPs’ monitoring in Thriassion Plain, and such strategies have to be a priority for Greek environmental authorities.

Continuous nationwide atmospheric PCDD/F monitoring network in Taiwan (2006-2016): Variation in concentrations and apportionment of emission sources

Atmospheric polychlorinated-dibenzo-dioxins/dibenzo-furans (PCDD/Fs) remains an important environmental health concern. Although the total emission inventories of PCDD/Fs in Taiwan decreased from 320 to 52.1 g-I-TEQ/year during 2002-2016, the resulting concentrations of atmospheric PCDD/F and distributions in Taiwan are unknown. We, therefore, conducted a comprehensive investigation of spatial and seasonal variations and apportioned potential sources of ambient PCDD/F concentrations in Taiwan-based on 11-year observation data. A total of 1,008 atmospheric PCDD/F samples were collected from 25 air monitoring stations (from seven areas) and 1 background station for 2006-2016. Linear regression was used to model changes in PCDD/F concentrations. Principal component analysis (PCA) and positive matrix factorization (PMF) were used to identify potential contributors. PCDD/F concentrations in the ambient air gradually decreased during the study period, with a median concentration of 28.2 fg I-TEQ/m3 over 11 years. The highest median PCDD/F concentrations were found in the highly industrialized regions of western Taiwan (38.0-43.4 fg I-TEQ/m3). Lower concentrations were found in eastern Taiwan (∼10 fg I-TEQ/m3). Background stations reported the lowest concentrations of PCDD/Fs, with a median concentration of 1.47 fg I-TEQ/m3. Overall, the concentrations of atmospheric PCDD/Fs in Taiwan were higher in winter (13.4-86.7 fg I-TEQ/m3) than in summer (9.65-27.2 fg I-TEQ/m3). The PCA results indicated that PCDD/F profiles varied by both region (industrialized, urbanized, and background areas) and season. The PMF model for the overall data revealed that the major sources of PCDD/Fs were industrial activities (71.2%). However, in less industrialized areas, traffic activities, long-range transport, and open burning were dominant.

PAH Profiles in Suspended Particulate Matter from an Urbanized River Within the Brazilian Amazon

The distribution, seasonal variation and sources of 16 polycyclic aromatic hydrocarbons (PAH) from suspended particulate matter (SPM) of the Aurá River, a small amazon typical river located in Northern Brazil, were determined. Gas chromatography-mass spectrometry analysis of SPM revealed a mixture of PAH from different origins and a seasonal variation of PAH primary source for the studied area. Pyrene was the dominant PAH in both studied periods. Total PAH content (ΣPAH) ranged from lower than quantification limit (< LOQ) to 2498.2 ng g^-1 dw during the dry season and < LOQ to 2865.8 ng g^-1 dw during the wet season. Low molecular weight PAH (LMW) represented 51% of ΣPAH during the dry season and 29% during the wet season. It was noted, by comparing previous data, that the main source of these compounds was altered after the deactivation of an irregular landfill next to the river.

Similar polycyclic aromatic hydrocarbon and genotoxicity profiles of atmospheric particulate matter from cities on three different continents

The extractable organic material (EOM) from atmospheric total suspended particles (TSP) contains several organic compounds including non-substituted polycyclic aromatic hydrocarbons (PAHs), alkyl-PAHs, and nitro-PAHs. These chemicals seem to be among the key drivers of TSP genotoxicity. We have shown previously that the mutagenic potencies of the EOM from Limeira, Stockholm, and Kyoto, cities with markedly different meteorological conditions and pollution sources are similar. Here we compare the profiles of non-substituted PAHs (27 congeners), alkyl-PAHs (15 congeners), and nitro-PAHs (7 congeners) from the same EOM samples from these cities. We also compared the genotoxicity profiles using comet and micronucleus assays in human bronchial epithelial cells. The profiles of PAHs, as well as the cytotoxic and genotoxic potencies when expressed in EOM, were quite similar among the studied cities. It seems that despite the differences in meteorological conditions and pollution sources of the cities, removal, mixing, and different atmospheric transformation processes may be contributing to the similarity of the PAHs composition and genotoxicity profiles. More studies are required to verify if this would be a general rule applicable to other cities. Although these profiles were similar for all three cities, the EOM concentration in the atmospheres is markedly different. Thus, the population of Limeira (∼10-fold more EOM/m³ than Stockholm and ∼6-fold more than Kyoto) is exposed to higher concentrations of genotoxic pollutants, and Kyoto's population is 1.5-fold more exposed than Stockholm's. Therefore, to reduce the risk of human exposure to TSP genotoxins, the volume of emissions needs to be reduced.

A prospective pilot study of the T-lymphocyte response to fine particulate matter exposure

Exposure to air pollution is associated with increased morbidity and mortality. Once the fine atmospheric particulate matter (FP) is inhaled, some of its compounds can pass through the lungs and reach the bloodstream where they can come into contact with immune cells. Exposure to FP particularly affects sensitive populations such as the elderly. Aging affects the immune system, making the elderly more vulnerable. The project aims to determine the effects of FP exposure on human T cells while looking for biomarkers associated with exposure. Blood samples from 95 healthy subjects in three different age groups (20-30, 45-55 and 70-85 years) were collected to determine a potential age effect. T lymphocytes were isolated to be exposed ex vivo for 72 hours to 45 μg/mL of FP collected in Dunkirk and chemically characterized. Overexpression of the CYP1A1, CYP1B1 and CYP2S1 genes was therefore measured after exposure of the T cells to FP. These genes code for enzymes known to be involved in the metabolic activation of organic compounds such as polycyclic aromatic hydrocarbons detected in the FP sample. T-cell profiling allowed us to suggest a mixed T-helper 1/2 profile caused by exposure to FP. With regard to the influence of age, we have observed differences in the expression of certain genes, as well as an increase in interleukin-4 and -13 concentrations in the elderly. These results showed that exposure of T lymphocytes to FP causes effects on both transcriptomic and cytokine secretion levels.

Characteristics, distribution, source and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in sediments along the Yangtze River Estuary Deepwater Channel

Characteristics, distribution, source, and ecological risk level of polycyclic aromatic hydrocarbons (PAHs) in sediments along Yangtze River Estuary Deepwater Channel were investigated. Total concentration of fifteen PAHs of study area ranged between 89.52 and 208.02 ng/g (mean value 140.48 ng/g). PAHs ratios and the statistical analysis showed that local fossil fuels high-temperature combustion (vehicular exhaust, anthropogenic combustion and pyrogenic sources) was the main PAHs origin. According to sediment quality guidelines (SQGs) and other criteria, the potential ecological risks of PAHs in sediments along Yangtze River Estuary Deepwater Channel are at low to medium levels, but the presence of dibenzo[a,h]anthracene (DBahAnt) requires more study and evaluation of potential toxicological effects.

Cellular response and extracellular vesicles characterization of human macrophages exposed to fine atmospheric particulate matter

Exposure to fine atmospheric Particulate Matter (PM) is one of the major environmental causes involved in the development of inflammatory lung diseases, such as chronic obstructive pulmonary disease (COPD) or asthma. When PM is penetrating in the pulmonary system, alveolar macrophages represent the first line of defense, in particular by triggering a pro-inflammatory response, and also by their ability to recruit infiltrating macrophages from the bone marrow. The aim of this in vitro study was to evaluate the gene expression and cytokine production involved in the toxicological and inflammatory responses of infiltrating macrophages, as well as the Extracellular Vesicles (EVs) production, after their exposure to PM. The ability of these EVs to convey information related to PM exposure from exposed macrophages to pulmonary epithelial cells was also evaluated. Infiltrating macrophages respond to fine particles exposure in a conventional manner, as their exposure to PM induced the expression of Xenobiotic Metabolizing Enzymes (XMEs) such as CYP1A1 and CYP1B1, the enzymes involved in oxidative stress SOD2, NQO1 and HMOX as well as pro-inflammatory cytokines in a dose-dependent manner. Exposure to PM also induced a greater release of EVs in a dose-dependent manner. In addition, the produced EVs were able to induce a pro-inflammatory phenotype on pulmonary epithelial cells, with the induction of the release of IL6 and TNFα proinflammatory cytokines. These results suggest that infiltrating macrophages participate in the pro-inflammatory response induced by PM exposure and that EVs could be involved in this mechanism.

Investigation on the near-field evolution of industrial plumes from metalworking activities

In a context where a significant fraction of the population lives near industrial areas, the main objectives of this study are to provide (a) new data on PM_2.5 chemical compositions, heavy-metal concentrations and trace gases released by metalworking activities and (b) new information on the near-field evolution (up to about a thousand meters) of such industrial plumes in terms of particle chemical composition and size distribution. For that purpose, a one-month field campaign was performed in an industrial area near the city of Dunkirk (Northern France), combining measurements of atmospheric dynamics and physico-chemical characterization of air masses. Comparisons between several elemental ratios (mainly Mn/Fe), particle size distributions and volatile organic compound (VOC) concentrations at the stacks and at a near-field site suggest that plumes of a ferromanganese alloy plant were quickly mixed with pollutants emitted by other sources (mainly other industries, possibly traffic and sea spray), in particular a neighboring steelworks, before reaching the sampling site. This led to the emergence of secondary particles related to condensation and/or aggregation phenomena inside the plumes. Metalworking emissions were also identified as a source of new particle formation, formed through the emission of gaseous precursors and their fast transformation and condensation, over a timescale of minutes before reaching the near-field site 800 m downwind. Ultrafine particles emitted at the stacks also quickly agglomerated to form larger particles before reaching the near-field site. These results show that, even over short distances, the chemical composition and size distribution of metalworking plumes may evolve rapidly and the characteristics of particles at the boundary of an industrial area (especially in contiguous urban areas) may differ from those emitted directly at the stacks.

In vitro evaluation of organic extractable matter from ambient PM2.5 using human bronchial epithelial BEAS-2B cells: Cytotoxicity, oxidative stress, pro-inflammatory response, genotoxicity, and cell cycle deregulation

A particular attention has been devoted to the type of toxicological responses induced by particulate matter (PM), since their knowledge is greatly complicated by the fact that it is a heterogeneous and often poorly described pollutant. However, despite intensive research effort, there is still a lack of knowledge about the specific chemical fraction of PM, which could be mainly responsible of its adverse health effects. We sought also to better investigate the toxicological effects of organic extractable matter (OEM) in normal human bronchial epithelial lung BEAS-2B cells. The wide variety of chemicals, including PAH and other related-chemicals, found in OEM, has been rather associated with early oxidative events, as supported by the early activation of the sensible NRF-2 signaling pathway. For the most harmful conditions, the activation of this signaling pathway could not totally counteract the ROS overproduction, thereby leading to critical oxidative damage to macromolecules (lipid peroxidation, oxidative DNA adducts). While NRF-2 is an anti-inflammatory, OEM exposure did not trigger any significant change in the secretion of inflammatory cytokines (i.e., TNFα, IL-1β, IL-6, IL-8, MCP-1, and IFNγ). According to the high concentrations of PAH and other related organic chemicals found in this OEM, CYP1A1 and 1B1 genes exhibited high transcription levels in BEAS-2B cells, thereby supporting both the activation of the critical AhR signaling pathway and the formation of highly reactive ultimate metabolites. As a consequence, genotoxic events occurred in BEAS-2B cells exposed to this OEM together with cell survival events, with possible harmful cell cycle deregulation. However, more studies are required to implement these observations and to contribute to better decipher the critical role of the organic fraction of air pollution-derived PM_2.5 in the activation of some sensitive signaling pathways closely associated with G1/S and intra-S checkpoint blockage, on the one hand, and cell survival, on the other hand.

An integrated functional and transcriptomic analysis reveals that repeated exposure to diesel exhaust induces sustained mitochondrial and cardiac dysfunctions

Diesel exhaust (DE) contributes to air pollution, an important risk factor for cardiovascular diseases. However, the mechanisms by which DE exposure induces cardiovascular dysfunction remain unknown and there is still debate on the contribution of the primary particulate matter (PM) fraction compared to the gaseous phase. Although the mitochondria play a key role in the events leading to cardiovascular diseases, their role in DE-induced cardiovascular effects has not been investigated. The aim of this study was to highlight cardiac and mitochondrial events that could be disrupted following acute and/or repeated DE exposures and the contribution of gaseous pollutants to these effects. To address this question, Wistar rats were exposed to DE generated under strictly controlled and characterized conditions and extracted upstream or downstream of the diesel particulate filter (DPF). Evaluation of the cardiac function after acute DE exposure showed a disturbance in echocardiographic parameters, which persisted and worsened after repeated exposures. The presence of the DPF did not modify the cardiovascular dysfunction revealing an important implication of the gas phase in this response. Surprisingly, redox parameters were not altered by DE exposures while an alteration in mitochondrial oxidative capacity was observed. Exploration of the mitochondrial function demonstrated a more specific alteration in complex I of the respiratory chain after repeated exposures, which was further confirmed by transcriptional analysis of left ventricular (LV) tissue. In conclusion, this work provides new insights into cardiovascular effects induced by DE, demonstrating a cardiac mitochondrial impairment associated with the gaseous phase. These effects suggest deleterious consequences in terms of cardiac function for vulnerable populations with underlying energy deficit such as patients with heart failure or the elderly.

Physico-chemical characterization and in vitro inflammatory and oxidative potency of atmospheric particles collected in Dakar city's (Senegal)

Exposure to atmospheric pollutants has been recognized as a major risk factor of respiratory and cardiovascular diseases. Fine particles (PM_2.5) and a coarser fraction (PM_>2.5) sampled at an urban site in Dakar (HLM), characterized by high road traffic emissions, were compared with particles sampled at a rural area, Toubab Dialaw located about 40 km from Dakar. The physicochemical characteristics of samples revealed that PMs differ for their physical (surface area) and chemical properties (in terms of CHN, metals, ions, paraffins, VOCs and PAHs) that were 65-75% higher in urban samples. Moreover the fine PMs contain higher amounts of anthropogenic related pollutants than the PM_>2.5 one. These differences are sustained by the ratios reported for the analysed PAHs which suggest as predominant primary emission sources vehicle exhausts at urban site and biomass combustion at the rural site. The inflammatory response and the oxidative damages were evaluated in BEAS-2B cells by the quantification of 4 selected inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-8) and of total carbonylated proteins and the oxidative DNA adduct 8-OHdG after 8 or 24 h exposure. In accordance with the different sources and different physical and chemical properties, the inflammatory response and the oxidative damages were found higher in bronchial cells exposed to urban PMs. These data confirm the importance, also for West African countries, to evaluate the correlation between PM physico-chemical properties and potential biological impacts.

Occurrence and distribution of pesticides in precipitation as revealed by targeted screening through GC-MS/MS

Facing the tough challenge of precise measurement of ever-increasing numbers of organic contaminants in the environment, there is an urgent need for more reliable and cost-effective methodologies. In this study, we developed and validated a screening method for analysis of over 450 pesticides in precipitation using gas chromatography with tandem mass spectrometry (GC-MS/MS) in multiple reaction monitoring (MRM) mode. Solid phase extraction (SPE) was applied to extract target analytes from precipitation. Using this targeted approach, we managed to detect 123 pesticides with maximum retention time shifts below 0.1 min (except for DEET) in 101 precipitation samples collected between October 2015 and March 2017 in Singapore. This is probably the first study to report the measurements of a wide range of pesticides in precipitation. A spectrum of insecticides, herbicides, fungicides and their synergists were detected and among them DEET, malathion and carbaryl were the most frequently detected pesticides (detection frequency: 100%, 96% & 67%). The Spearman correlations suggest that some pesticides of different subgroups had significant correlations. It is believed that these finding could shed light on the understanding of the contribution of precipitation to environmental contaminants in water cycle.

Polycyclic aromatic hydrocarbons in sediments of the Amazon River Estuary (Amapá, Northern Brazil): Distribution, sources and potential ecological risk

The distribution, sources and potential ecological risk of priority polycyclic aromatic hydrocarbons (PAHs) in sediment from the Amazon River Estuary (Macapá and Santana, Amapá, Northern Brazil) were investigated. The total PAHs concentration (∑PAH) ranged from 22.2 to 158.9 ng g^-1 dw (mean value 49.4 ng g^-1 dw). PAHs levels in the study area were relatively low than those in nearby areas and other coastal zones worldwide, and could be considered as baseline for PAHs in Amazonic sediments. PAHs ratios and the statistical analysis showed that fossil fuel and biomass combustions, primarily from local sources, were the dominant PAHs origins. The potential ecological risk was assessed on the basis of the sediment quality guidelines, and it was found that PAHs in the sediments of the Amazon River Estuary do not cause adverse effects on living organisms; however, the abundance of naphthalene and the presence of dibenzo[a,h]anthracene and benzo[a]pyrene deserve more attention.

Chemical characterization of fine and ultrafine PM, direct and indirect genotoxicity of PM and their organic extracts on pulmonary cells

Particulate matter in ambient air constitutes a complex mixture of fine and ultrafine particles composed of various chemical compounds including metals, ions, and organics. A multidisciplinary approach was developed by studying physico-chemical characteristics and mechanisms involved in the toxicity of particulate atmospheric pollution. PM_0.3-2.5 and PM_2.5 including ultrafine particles were sampled in Dunkerque, a French industrialized seaside city. PM samples were characterized from a chemical and toxicological point of view. Physico-chemical characterization evidenced that PM_2.5 comes from several sources: natural ones, such as soil resuspension and marine sea-salt emissions, as well as anthropogenic ones, such as shipping traffic, road traffic, and industrial activities. Human BEAS-2B lung cells were exposed to PM_0.3-2.5, or to the Extractable Organic Matter (EOM) of PM_0.3-2.5 and PM_2.5. These exposures induced several mechanisms of action implied in the genotoxicity, such as oxidative DNA adducts and DNA Damage Response. The toxicity of PM-EOM was higher for the sample including the ultrafine fraction (PM_2.5) containing also higher concentrations of polycyclic aromatic hydrocarbons. These results evidenced the major role of organic compounds in the toxicity of PM.

Concentration, distribution and source apportionment of polycyclic aromatic hydrocarbons (PAH) in Poxim River sediments, Brazil

The individual concentrations, total amount and sources of 16 priority polycyclic aromatic hydrocarbons (PAH) in sediments collected along of the Poxim River, Aracaju, Brazil, were for the first time determined. The ΣPAH ranged between 2.2±1.5ngg^-1 and 28.4±6.9ngg^-1, with a mean value of 14.4±9.3ngg^-1. The Pearson correlation test and Principal component analysis (PCA) were used to assess the correlation between the PAH, organic matter and grain size; and to differentiate the sampling stations. Diagnostic ratios presented predominance of pyrogenic sources. Therefore, the PAH quantified showed the influence of anthropogenic activities near of the Poxim River.

Fine particles at a background site in Central France: Chemical compositions, seasonal variations and pollution events

To expand our knowledge of regional fine particles in Central France (Centre-Val de Loire region), a field observation study of PM_2.5 was carried out at Verneuil site (46.81467N, 2.61012E, 180m.a.s.l.) from 2011 to 2014. The mass concentrations of water-soluble inorganic ions (WSIIs), organic carbon (OC), elemental carbon (EC) and biomass burning tracer (Levoglucosan) in PM_2.5 were measured. Annual average PM_2.5 mass concentrations were 11.8, 9.5, 12.6 and 10.2μg·m^-3 in 2011, 2012, 2013 and 2014, respectively, three of four higher than the WHO guideline of 10μg·m^-3. Secondary inorganic aerosol (SIA) and organic matter (OM) appeared to be the major components in PM_2.5 in Verneuil, contributing 30.1-41.8% and 36.9-46.3%, respectively. Main chemical species were observed in the following order: winter≥spring>autumn>summer. Backward atmospheric trajectories were performed using Hysplit model and suggested that the PM_2.5 pollutants caused by atmospheric transport were mainly originated from European inland, mainly east to north-east areas. During the observation period, five pollution events were reported and indicated that not only the polluted air masses from central Europe but also the biomass burning from East Europe significantly influenced the air quality in Verneuil site.

Particulate metal bioaccessibility in physiological fluids and cell culture media: Toxicological perspectives

According to the literature, tiny amounts of transition metals in airborne fine particles (PM_2.5) may induce proinflammatory cell response through reactive oxygen species production. The solubility of particle-bound metals in physiological fluids, i.e. the metal bioaccessibility is driven by factors such as the solution chemical composition, the contact time with the particles, and the solid-to-liquid phase ratio (S/L). In this work, PM_2.5-bound metal bioaccessibility was assessed in various physiological-like solutions including cell culture media in order to evidence the potential impact on normal human bronchial epithelial cells (NHBE) when studying the cytotoxicity and inflammatory responses of PM_2.5 towards the target bronchial compartment. Different fluids (H₂O, PBS, LHC-9 culture medium, Gamble and human respiratory mucus collected from COPD patients), various S/L conditions (from 1/6000 to 1/100,000) and exposure times (6, 24 and 72h) were tested on urban PM_2.5 samples. In addition, metals' total, soluble and insoluble fractions from PM_2.5 in LHC-9 were deposited on NHBE cells (BEAS-2B) to measure their cytotoxicity and inflammatory potential (i.e., G6PDH activity, secretion of IL-6 and IL-8). The bioaccessibility is solution-dependent. A higher salinity or organic content may increase or inhibit the bioaccessibiliy according to the element, as observed in the complex mucus matrix. Decreasing the S/L ratio also affect the bioaccessibility depending on the solution tested while the exposure time appears less critical. The LHC-9 culture medium appears to be a good physiological proxy as it induces metal bioaccessibilities close to the mucus values and is little affected by S/L ratios or exposure time. Only the insoluble fraction can be linked to the PM_2.5-induced cytotoxicity. By contrast, both soluble and insoluble fractions can be related to the secretion of cytokines. The metal bioaccessibility in LHC-9 of the total, soluble, and insoluble fractions of the PM_2.5 under study did not explain alone, the cytotoxicity nor the inflammatory response observed in BEAS-2B cells. These findings confirm the urgent need to perform further toxicological studies to better evaluate the synergistic effect of both bioaccessible particle-bound metals and organic species.

Fine and ultrafine atmospheric particulate matter at a multi-influenced urban site: Physicochemical characterization, mutagenicity and cytotoxicity

Particulate Matter (PM) air pollution is one of the major concerns for environment and health. Understanding the heterogeneity and complexity of fine and ultrafine PM is a fundamental issue notably for the assessment of PM toxicological effects. The aim of this study was to evaluate mutagenicity and cytotoxicity of a multi-influenced urban site PM, with or without the ultrafine fraction. For this purpose, PM_2.5-0.3 (PM with aerodynamic diameter ranging from 0.3 to 2.5 μm) and PM_2.5 were collected in Dunkerque, a French coastal industrial city and were extensively characterized for their physico-chemical properties, including inorganic and organic species. In order to identify the possible sources of atmospheric pollution, specific criteria like Carbon Preference Index (CPI) and PAH characteristic ratios were investigated. Mutagenicity assays using Ames test with TA98, TA102 and YG1041 Salmonella strains with or without S9 activation were performed on native PM sample and PM organic extracts and water-soluble fractions. BEAS-2B cell viability and cell proliferation were evaluated measuring lactate dehydrogenase release and mitochondrial dehydrogenase activity after exposure to PM and their extracts. Several contributing sources were identified in PM: soil resuspension, marine emissions including sea-salt or shipping, road traffic and industrial activities, mainly related to steelmaking or petro-chemistry. Mutagenicity of PM was evidenced, especially for PM_2.5, including ultrafine fraction, in relation to PAHs content and possibly nitro-aromatics compounds. PM induced cytotoxic effects at relatively high doses, while alteration of proliferation with low PM doses could be related to underlying mechanisms such as genotoxicity.